Fast-Response Sensitivity-Enhanced All-Fiber Fabry–Pérot High-Pressure Sensor for Internal Combustion Engines

A novel fast-response sensitivity-enhanced high-temperature all-fiber Fabry–Pérot high-pressure sensor formed with a hard-core diaphragm is proposed and demonstrated. The structure can effectively improve device pressure sensitivity and eliminate additional reflection interference from the outer surface. Theoretical and experimental results show that sensor pressure sensitivity increased to approximately two times the original value when the diaphragm thickness is decreased from 5 mm to 11 μm. Moreover, simulation analysis indicates that sensors with different diaphragm thicknesses, from 10 μm to 2 mm, all possess high mechanical resonant frequency exceeding 100 kHz. In addition, a sensor was tested based on an intensity demodulation method and demonstrated a stable pressure sensitivity of 0.23 V/MPa, a hysteresis of less than 1.5%, and repeatability accuracy of less than 0.8% in the range of 40–200 °C. Field dynamic tests in a diesel engine demonstrated that the fiber sensor not only has an excellent dynamic characteristic but is also consistent with a commercial Kistler sensor.